DESCRIPTION: The investigators propose to test the feasibility of developing lead iodide semiconductor film for use as a target in an X- ray electron beam imaging tube designed for mammography, as further described by their abstract: The goal of the proposed project is to develop high resolution digital imaging system for mammography using an X-ray, electron beam imaging tube (XEBIT). The heart of XEBIT is a semiconductor target, which performs the vital function of converting the X-ray image directly into an electronic charge image, which is then read-out by a scanning electron beam. Due to minimal lateral spread of charge carriers, very high spatial resolution is possible in XEBIT. While the read-out scheme is straight forward, the key to making this promising approach work is to develop the target with appropriate properties. We have identified a target material, PbI2, which is very promising for mammography due to its high X-ray absorption, large gain, high dielectric constant, and good electrical properties. Based on these properties, PbI2 targets are expected to operate with high signal/noise ratio (and be X-ray photon noise limited), provide excellent intrinsic spatial resolution (>100 lp/mm), and wide dynamic range. The Phase I project will specifically focus on preparation and characterization of PbI2 films as XEBIT targets and thereby demonstrate the feasibility of producing high spatial resolution, large area mammographic imaging systems. Such systems will surpass the performance of currently used film-screens and thereby facilitate better diagnosis of breast cancer. PROPOSED COMMERCIAL APPLICATION: An imaging tube with adequate quantum efficiency and 20 line pair/mm resolution or better would have high commercial potential.